The invention relates to a conductor strip arrangement for a molded electronic component where at least one semiconductor element is located on an electrically conducting conductor strip, and where around the conductor strip and the at least one semiconductor element a housing made of a molding material is arranged such that there are still sections of the conductor strip outside the housing, and a process for molding a housing of an electronic component in a mold form, with the component featuring an electrically conducting conductor strip and connection pins located to one side, and the conductor strip having a frame with frame sections, which forms the lateral boundary between the top and bottom sections of the mold form and whose diameter essentially is slightly larger than the diameter of the actual mold form.
Such a molded electronic component is known, for example, from the German patent publication DE 196 53 054 A1. In the case of such molded electronic components, semiconductor chips (optoelectronic transmitter and receiver, integrated circuit for signal processing) are first glued or soldered by machine onto a metal conductor strip and then contacted to one another and with the conductor strip by means of thin gold or aluminum wires. Then, using a mold process, semiconductor chips and conductor strips will in most cases be enveloped by means of a thermoplastic material such as a synthetic resin, for example, thereby creating a housing for the protection of this assembly.
When the housing is manufactured, there remains an edge or protrusion of mold material in the separation plane of the mold form, between the top and bottom sections, which edge is also designated as a xe2x80x9cridgexe2x80x9d. This is particularly disadvantageous if the ridge runs through that surface of the housing which a suction needle from an automatic assembly machine will be docking onto at a later time, in order to take up the component and place the same onto a printed circuit board, for instance. Due to the ridge the suction needle does not connect tightly but draws in a great deal of external air, thus causing insufficient holding suction for any component to be taken up. In addition, when it is taken up the component will tilt over and assume a tilted and non-definable position on the suction needle. For this reason, an unacceptably large number of components are lost during transportation or are positioned imprecisely.
It is therefore attempted to keep the ridge as small as possible; however, this requires mold tools with very strict tolerances, very precise manufacturing, and additional controls. But these measures lead to significantly increased manufacturing costs without the problem having been really solved.
It is an object of the invention to develop a conductor strip arrangement for a molded electronic component of the above mentioned general type, such that it can be taken up without difficulty by an automatic assembly machine and placed on a printed circuit board. It is furthermore an object of the invention to provide a process for molding such an electronic component.
According to the invention, the above objects have been achieved by a conductor strip arrangement and a molding process having the following special features.
Particularly, the invention provides a conductor strip arrangement for a molded electronic component where at least one semiconductor element is located on an electrically conducting conductor strip, and where a housing made of a molding material is arranged around the conductor strip and the at least one semiconductor element such that there are still sections of the conductor strip outside the housing, wherein sections of the conductor strip feature a widening such that these widened sections of the conductor strip are directly adjacent to the housing or even protrude somewhat into the housing in order to prevent a mold material ridge from forming on the housing. The widened sections are not embedded and not fixed in the molding material, so that they are free and removable from the molded housing.
The invention further provides a process for molding a housing of an electronic component in a mold form, with the component featuring an electrically conducting conductor strip and connection pins located to one side, and the conductor strip having a frame with frame sections, which forms the lateral boundary between the top and bottom sections of the mold form and whose diameter essentially is slightly larger than the diameter of the actual mold form, wherein a frame section features a widening directly adjacent to the mold form or even protruding somewhat into the mold form in order to prevent the formation of a mold material ridge on the housing. Finally, the widening of the frame section is removed from the housing.
The molded electronic components manufactured in accordance with the invention feature the advantage that they can be take up without difficulty, held securely and placed exactly, by automatic assembly machines without particularly strict tolerances having to be maintained during the production of the molded electronic component or any special tools having to be used for its production.
The invention is particularly suitable for the production of electronic components whose separation plane runs through that housing surface which serves as docking surface for a suction needle from an assembly machine.
In the following the invention will be explained by means of an embodiment example and the drawing.